Method for removing sulfur-containing contaminants from a thermally cracked waste oil

Abstract

A method for removing sulfur containing contaminants from a thermally cracked waste oil is disclosed. In the present invention, the substantial amount of contaminants containing sulfur is separated into a solvent and further remaining contaminants can be separated via adsorption with bauxite such that an end product oil having better quality may be produced with higher productivity. The solvent can be subject to flash evaporation and then be recycled.

What is claimed is: 
     
       1. A method for removing sulfur-containing contaminants from a thermally cracked waste oil comprising the steps of:
 mixing the thermally cracked waste oil with a solvent; 
 extracting first sulfur-containing contaminants within the thermally cracked waste oil into the solvent; 
 filtering an oil phase of the thermally cracked waste oil through bauxite columns; 
 extracting second sulfur-containing contaminants within the oil phase filtered through the bauxite columns into the solvent; and 
 separating the solvent containing the first and the second sulfur-containing contaminants from the oil phase. 
 
     
     
       2. The method of  claim 1 , wherein the solvent is an acetone or a mixture of an acetone and a methanol. 
     
     
       3. The method of  claim 2 , wherein the acetone has 100% purity. 
     
     
       4. The method of  claim 1 , further comprising steps of:
 applying a flash evaporation to the solvent containing the first and the second sulfur-containing contaminants, thereby separating the first and the second sulfur-containing contaminants from the solvent to obtain a recycled solvent; and 
 reusing the recycled solvent for the step of the mixing the thermally cracked waste oil with the solvent. 
 
     
     
       5. The method of  claim 1 , wherein the extracting the first sulfur-containing contaminants is repeated at least three times. 
     
     
       6. The method of  claim 2 , wherein a ratio of acetone:methanol in the mixture is 80:20 by volume. 
     
     
       7. The method of  claim 1 , wherein a temperature for the extracting ranges 50-70° C. 
     
     
       8. The method of  claim 1 , wherein a temperature for the extracting ranges 55-60° C. 
     
     
       9. The method of  claim 1 , wherein the thermally cracked waste oil comprises engine oil, metal cutting oil, hydraulic oil, or a mixture thereof. 
     
     
       10. The method of  claim 1 , wherein the extracting is conducted in an atmospheric pressure. 
     
     
       11. The method of  claim 1 , wherein a volume ratio of the solvent and the thermally cracked waste oil is 50:50. 
     
     
       12. The method of  claim 1 , wherein a volume ratio of the solvent and the oil phase is 50:50. 
     
     
       13. The method of  claim 1 , wherein the mixing is conducted 0-20 min after a thermal cracking of a waste oil. 
     
     
       14. The method of  claim 1 , wherein the extracting is conducted for 30-60 min. 
     
     
       15. The method of  claim 4 , wherein the flash evaporation comprises:
 condensing the solvent containing the first and the second sulfur-containing contaminants; 
 separating a sludge cake from the condensed solvent; and 
 discharging the sludge cake. 
 
     
     
       16. The method of  claim 4 , wherein a temperature of the solvent at the end of the condensing ranges 65-75° C. 
     
     
       17. The method of  claim 1 , further comprising:
 cooling the oil phase to a room temperature; and 
 pumping the oil phase into the bauxite columns. 
 
     
     
       18. The method of  claim 17 , wherein the pumping is adjusted such that a residence time of the oil phase within the bauxite columns is maintained at about 10-12 hrs.